The invention relates to a handheld machine tool according to the generic part of claim 1.
A handheld grinding tool known from DE-OS 44 21 480 carries a grinding disk on its driven shaft between two clamping flanges. The outer clamping flange can be tightened against the grinding disk via a thread. The inner flange is supported so as to be rotatable relative to the driven spindle with low friction by means of a solid lubricant. When the outer clamping flange is rotated in the loosening direction, the inner clamping flange can easily be rotated jointly with the grinding disk. Therefore, the outer clamping flange can be loosened by slight force and the grinding disk can be exchanged easily.
This solution has the disadvantage that the outer flange tries to loosen when the grinding spindle is braked abruptly, resulting in the risk that the grinding disk will spin away from the grinding spindle with great force which leads to a corresponding risk of injury to persons in the vicinity.
Since the self-clamping effect in the prior art resulting from the fact that the clamping screw was carried along by the saw blade could be so great that the clamping screw could not be loosened manually but only by means of a tool, it was always necessary to bring along a tool and, in most cases, to use it for changing the saw blade. This was accordingly time-consuming.
EP 0 231 500 discloses fast-clamping systems for easy detachment of grinding disks, saw blades or the like in handheld machine tools which operate satisfactorily, but which, when the tool shaft is stopped, do not automatically reduce the clamping torque in such a way that the tool can be detached easily by rotating the outer clamping flange manually.